This invention relates to valves, and more particularly to valves employing radial sealing surfaces with resilient seals there-between. In the preferred embodiment, the radial seal is employed in conjunction with a conventional metal-to-metal poppet and seat arrangement to provide a dual acting check valve.
Some aircraft systems require the storage of energy in accumulators for emergency operation. Typically, these accumulators store hydraulic fluid under pressure by compressing a gas on one side of a piston or bladder and are charged automatically through check valves. It is essential that these check valves be leakproof or the charge of pressure will be lost and the system will not function when required. Somewhat similar systems employing high pressure pneumatics as the system muscle in missile and space applications also require zero leakage check valves.
The prior art reflects many attempts to develop zero leakage check valves employing resilient sealing means. All of these efforts are centered around face seal applications of the soft seal. The most popular approach has been a conical poppet, housing an o-ring, which mates against a tapered seat which is generally considered a face seal as opposed to a pure radial seal. In all these applications, no matter what novel means are employed to shroud the soft seal, the seal is exposed to some degree of fluid flow during opening and closing of the valve. Flow exposure tends to wash the seal from its containment groove which erodes the seal.
The most effective zero leakage check valve commercially available to date employs precision metal-to-metal, extremely hard, and optically flat sealing surfaces, one of which is provided with a pair of closely spaced, concentric, circular, sharp-edge, raised members. This valve, while enjoying a degree of success, is very expensive and will leak when the conditions are such that the valve seal closes slowly.